TRH mimetics: differentiation of antiamnesic potency from antidepressant effect

New Glutamine-Containing Substrates for the Assay of Cysteine Peptidases From the C1 Papain Family

New substrates with glutamine in the P1-position are introduced for the assay of peptidases from the C1 papain family, with a general formula of Glp-Phe-Gln-X, where Glp is pyroglutamyl and X is pNA (p-nitroanilide) or AMC (4-amino-7-methylcoumaride). The substrates have a simple structure, and C1 cysteine peptidases of various origins cleave them with high efficiency. The main advantage of the substrates is their selectivity for cysteine peptidases of the C1 family. Peptidases of other clans, including serine trypsin-like peptidases, do not cleave glutamine-containing substrates. We demonstrate that using Glp-Phe-Gln-pNA in combination with a commercially available substrate, Z-Arg-Arg-pNA, provided differential determination of cathepsins L and B. In terms of specific activity and kinetic parameters, the proposed substrates offer improvement over the previously described alanine-containing prototypes. The efficiency and selectivity of the substrates was demonstrated by the example of chromatographic and electrophoretic analysis of a multi-enzyme digestive complex of stored product pests from the Tenebrionidae family.

Homo- and heptanor-sterols and tremulane sesquiterpenes from cultures of Phellinus igniarius

Four steroids, a homopregnene (1) and three heptanorergosterane derivatives (2-4), nine tremulane sesquiterpenes (5-13), and 18 known compounds have been isolated from cultures of the fungus Phellinus igniarius. Their structures and absolute configurations were elucidated by spectroscopic data analysis. In preliminary in vitro assays, at 10(-5) M, compounds 8, 9, 13, and 3beta-hydroxy-11,12-O-isopropyldrimene (14) showed significant vascular-relaxing activities against phenylephrine-induced vasoconstriction with relaxing rates of 35.7%, 45.4%, 46.6%, and 32.1%, respectively, as compared with the blank control.

Dominant-submissive behavior as models of mania and depression

This review examines the ways in which dominant-subordinate behavior in animals, as determined in laboratory studies, can be used to model depression and mania in humans. Affective disorders are mood illnesses with two opposite poles, melancholia (depression) and mania that are expressed to different degrees in affected individuals. Dominance and submissiveness are also two contrasting behavioral poles distributed as a continuum along an axis with less or more dominant or submissive animals. The premise of this article is that important elements of both mania and depression can be modeled in rats and mice based on observation of dominant and submissive behavior exhibited under well defined conditions. Studies from our own research, where dominance and submissiveness are defined in a competition test and measured as the relative success of two food-restricted rats to gain access to a feeder, have yielded a paradigm that we call the Dominant Submissive Relationship (DSR). This paradigm results in two models sensitive to drugs used to treat mood disorders. Specifically, drugs used to treat mania inhibit the dominant behavior of rats gaining access to food at the expense of an opponent (Reduction of Dominant Behavior Model or RDBM), whereas antidepressants counteract the behavior of rats losing such encounters; Reduction of Submissive Behavior Model (RSBM). The validation of these models, as well as their advantages and limitations, are discussed and compared with other animal paradigms that utilize animal social behavior to model human mood disturbances.

Central nervous system effects of thyrotropin-releasing hormone and its analogues: opportunities and perspectives for drug discovery and development

Besides its well-known endocrine role in the thyroid system, thyrotropin-releasing hormone (L-pyroglutamyl-L-histidyl-L-prolinamide) has been long recognized as a modulatory neuropeptide. After a brief overview of the extrahypothalamic and receptor distribution, and of the neurophysiological, neuropharmacological and neurochemical effects of this tripeptide, this review discusses efforts devoted to enhance therapeutically beneficial central nervous system effects via structural modifications of the endogenous peptide. An enormous array of maladies affecting the brain and the spinal cord has been a potential target for therapeutic interventions involving agents derived from thyrotropin-releasing hormone as a molecular lead. Successful development of several centrally active analogues and recent accounts of efforts aimed at improving metabolic stability, selectivity and bioavailability are highlighted.